JP2005003093A - Internal combustion engine with double link type connecting rod mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the speed of a piston after a top dead center without excessively increasing pressure on the piston. <P>SOLUTION: This internal combustion engine comprises the piston 30 and a crank shaft 40 connected together via a double link type connection rod mechanism 50. The double link type connection rod mechanism 50 consists of a first connection link 52, a second connection link 54, and a supporting link 56. A value for a connection rod ratio represented by the ratio of the length of the first connection link 52 to the length of a crank arm portion 44 of the crank shaft 40 is set to be 1.0 or greater and 2.0 or smaller. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internal combustion engine having a multi-link connecting rod mechanism.
[0002]
[Prior art]
The piston-crank mechanism includes a single link type and a multi-link type. The single link type piston-crank mechanism is a mechanism in which a piston and a crankshaft are connected by a single link (connecting rod). The multi-link type piston-crank mechanism is a mechanism in which a piston and a crankshaft are connected by a connecting rod group constituted by a plurality of links. A connecting rod group constituted by a plurality of links is called a “multi-link connecting rod mechanism”.
[0003]
By the way, knocking in a gasoline engine generally occurs when the end gas spontaneously ignites after ignition. Therefore, in order to prevent knocking, the piston speed after top dead center should be increased to reduce the pressure / temperature of the end gas. For this purpose, it is known that in the single link type piston-crank mechanism, the ratio (continuous ratio) between the length of the connecting rod and the length of the crank arm portion of the crankshaft should be reduced.
[0004]
On the other hand, regarding a multi-link type piston-crank mechanism, for example, Patent Document 1 discloses a technique for changing a piston speed.
[0005]
[Patent Document 1]
JP 2001-342859 A [Patent Document 2]
JP 2001-263113 A [Patent Document 3]
Japanese Patent Laid-Open No. 62-35033
[Problems to be solved by the invention]
However, the technique of Patent Document 1 reduces the piston stroke speed around the top dead center, and has an adverse effect on knocking. As described above, in the conventional multi-link type piston-crank mechanism, there is no known technique that makes it difficult for knocking to occur by increasing the piston speed after top dead center.
[0007]
On the other hand, in the single link type piston-crank mechanism, when the piston ratio after top dead center is increased by reducing the value of the linkage ratio, the side pressure acting on the piston is excessively increased by the combustion load. was there. That is, to reduce the linkage ratio is to shorten the length of the connecting rod, and at this time, the angle formed between the axial center line of the cylinder and the axial center line of the connecting rod increases. Accordingly, the side pressure acting on the piston is increased, resulting in a problem that the friction is increased and the wear of the piston skirt is also increased.
[0008]
The present invention has been made to solve the above-described conventional problems, and provides a technique capable of increasing the piston speed after top dead center without excessively increasing the side pressure acting on the piston. For the purpose.
[0009]
[Means for solving the problems and their functions and effects]
In order to achieve the above object, a first internal combustion engine of the present invention includes:
A cylinder,
A piston that reciprocates in the cylinder;
A crankshaft that rotates around a drive shaft;
A multi-link connecting rod mechanism connecting the piston and the crankshaft;
With
The multi-link connecting rod mechanism is rotatably connected to the crankshaft, is rotatably connected to the first connecting link, and is connected to the piston via a piston pin. A second connection link; and a support link rotatably connected to a connection portion between the first connection link and the second connection link and fixed to a support point of the internal combustion engine body. Prepared,
A linkage ratio value represented by a ratio between the length of the first connection link and the length of the crank arm portion of the crankshaft is set to a value of 1.0 or more and 2.0 or less. And
[0010]
In this internal combustion engine, the angle between the axial center line of the cylinder and the axial center line of the second connecting link (hereinafter referred to as “runout angle φ”) is determined as the value of the connecting rod of the single link piston-crank mechanism. The value can be made smaller than the deflection angle. That is, with the reciprocating motion of the piston, the second connecting link can be moved in a state close to being parallel to the axial center line of the cylinder. This is because the lower end portion of the second connecting link (the connecting portion with the first connecting link) reciprocates on an arc whose center is the point supporting the support link of the internal combustion engine body and whose radius is the length of the support link. Therefore, the distance between the lower end portion of the second connecting link and the axial center line of the cylinder can be kept within a small range. On the other hand, in the single link type piston-crank mechanism, the lower end portion (connecting portion with the crankshaft) of the connecting rod rotates on a circumference whose center is the crankshaft drive shaft and whose radius is the length of the crankarm. Therefore, the distance between the lower end portion of the connecting rod and the axial center line of the cylinder is increased, and the deflection angle φ is increased. The swing angle φ in the single link type piston-crank mechanism means an angle formed by the axial center line of the cylinder and the axial center line of the connecting rod.
[0011]
As described above, in this internal combustion engine, with the reciprocating motion of the piston, the second connecting link moves in a state close to being parallel to the axial center line of the cylinder. Accordingly, the first connecting link works like a connecting rod in a single link type piston-crank mechanism. Therefore, the linkage ratio in the internal combustion engine is substantially represented by the ratio between the length of the first connecting link and the length of the crank arm portion of the crankshaft. Similarly to the single link type piston-crank mechanism, the piston speed after top dead center can be increased by shortening the length of the first connecting link and setting the linkage ratio to a small value.
[0012]
Here, in this internal combustion engine, by shortening the length of the first connecting link, the trajectory of the upper end portion of the first connecting link (the connecting portion with the second connecting link) becomes the lower end portion of the first connecting link ( Even if it overlaps with the circumference that is the locus of the connecting portion with the crankshaft, no problem occurs. This is because the presence of the second connecting link prevents the interference between the piston and the crankshaft. Therefore, the value of the linkage ratio can be set small, and the piston speed after top dead center can be increased.
[0013]
Further, in this internal combustion engine, the value of the deflection angle φ can be set within a small range, so that the side pressure acting on the piston can be kept small.
[0014]
The multi-link connecting rod mechanism may be configured such that the axial center line of the second connecting link is parallel to the axial center line of the cylinder after the top dead center of the piston.
[0015]
The combustion load acting on the piston is large after top dead center. Therefore, according to this configuration, the deflection angle φ when the combustion load is large is reduced, and the side pressure acting on the piston can be further suppressed.
[0016]
The axial center line of the cylinder may be offset so that the distance from the support point of the internal combustion engine body is closer than the drive shaft of the crankshaft.
[0017]
According to this configuration, the swing angle φ can be reduced even if the linkage ratio value is reduced, and the piston speed after top dead center can be increased without excessively increasing the side pressure acting on the piston. Can do.
[0018]
The second internal combustion engine of the present invention is
A cylinder,
A multi-link piston-crank mechanism;
With
The multi-link piston-crank mechanism includes a piston that reciprocates in the cylinder, a crankshaft that rotates about a drive shaft, and a multi-link connecting rod mechanism that connects the piston and the crankshaft by a plurality of links. And comprising
The multi-link piston-crank mechanism is closer to the top dead center of the piston than a single-link piston-crank mechanism configured so that the stroke of the piston has the same value as the multi-link piston-crank mechanism. The piston speed change rate is configured to be large.
[0019]
Also in this internal combustion engine, by adopting a multi-link type connecting rod mechanism, the piston near the top dead center of the piston is compared with a single link type piston-crank mechanism without excessively increasing the side pressure acting on the piston. The rate of speed change can be increased. That is, the piston speed before and after the piston top dead center can be increased.
[0020]
In addition, this invention can be implement | achieved in various aspects, for example, can be implement | achieved in aspects, such as a moving body provided with a piston-crank mechanism, an internal combustion engine, an external combustion engine, and the engine.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in the following order based on examples.
A. Example:
B. Variation:
[0022]
A. Example:
FIG. 1 is a conceptual diagram showing a configuration of a piston-crank mechanism in an internal combustion engine as one embodiment of the present invention. This mechanism includes a cylinder 20, a piston 30, a crankshaft 40, and a multi-link connecting rod mechanism 50.
[0023]
The multi-link connecting rod mechanism 50 includes a first connection link 52, a second connection link 54, and a support link 56. The first connection link 52 and the second connection link 54 are rotatably connected by a connection pin 58. A lower end of the first connection link 52 is rotatably connected to an end portion of the crank arm portion 44 of the crankshaft 40 by a crank pin 46. The upper end of the second connection link 54 is rotatably connected to the piston 30 by the piston pin 32. The support link 56 is rotatably connected to a connection portion between the first connection link 52 and the second connection link 54 by a connection pin 58, and at the opposite end, a support point of an internal combustion engine body (not shown). It is fixed so that it can rotate.
[0024]
When the piston 30 reciprocates up and down, the crankshaft 40 rotates about its drive shaft 42. In FIG. 1, a connecting portion (such as the drive shaft 42) indicated by a black circle rotates or rotates around the axis, but does not change its relative position with the cylinder 20 (hereinafter referred to as “fulcrum”). ). Further, a connecting portion (a connection pin 58 or the like) represented by a white circle rotates or rotates around its axis and changes its relative position to the cylinder 20 (hereinafter referred to as “moving connection point”). ).
[0025]
The internal combustion engine of the present embodiment includes the same various components (valves, intake pipes, exhaust pipes, etc.) as a normal internal combustion engine, but FIG. It is omitted.
[0026]
2 (A) to 2 (D) are explanatory views showing changes in the shape of the piston-crank mechanism accompanying the movement of the piston 30. FIG. 2A shows a state when the piston 30 is at the top dead center, and FIG. 2C shows a state when the piston 30 is at the bottom dead center. 2A to 2D, various connection points and lines are represented as follows.
(1) Moving connection point A: central axis of the piston pin 32 (FIG. 1).
(2) Moving connecting point B: A connecting point at the end of the second connecting link 54 opposite to the moving connecting point A.
(3) Moving connecting point C: A connecting point at the end of the first connecting link 52 opposite to the moving connecting point B.
(4) Support point D: A connection point at the end of the support link 56 opposite to the moving connection point B.
(5) Support point E: drive shaft 42 (FIG. 1) of the crankshaft 40 (FIG. 1).
(6) Line ZZ: axial center line of cylinder 20 (7) Line XX: passing through fulcrum E (drive shaft 42 of crankshaft 40), line ZZ (axial center line of cylinder 20) Line perpendicular to [0027]
The moving connection point A moves in the vertical direction (the ZZ direction in FIG. 2) as the piston 30 reciprocates. The moving connection point B reciprocates on an arc around the fulcrum D as the movement connection point A moves. The moving connection point C rotates on the circumference around the fulcrum E as the movement connection point B moves.
[0028]
In the piston-crank mechanism in the present embodiment, the value of the angle (runout angle φ) formed by the line ZZ (the axial center line of the cylinder 20) and the axial center line of the second connecting link 54 is a single link type. The value is smaller than the deflection angle of the connecting rod in the piston-crank mechanism. That is, with the reciprocating motion of the piston 30, the second connection link 54 moves in a state close to being parallel to the line ZZ. This is because the moving connection point B (the lower end portion of the second connection link 54) reciprocates on an arc whose center is the fulcrum D and whose radius is the length of the support link 56. This is because the distance from Z falls within a small range. On the other hand, in the single link type piston-crank mechanism, the lower end portion of the connecting rod rotates on a circumference whose center is the crankshaft drive shaft and whose radius is the length of the crank arm. Therefore, the distance between the lower end portion of the connecting rod and the axial center line of the cylinder is increased, and the deflection angle φ is increased.
[0029]
The linkage ratio in the present embodiment is represented by the ratio between the length of the first connecting link 52 and the length of the crank arm portion 44 of the crankshaft 40 (FIG. 1). In the present embodiment, this is because the second connecting link 54 moves in a state close to being parallel to the line ZZ (the axial center line of the cylinder 20), so that the first connecting link 52 is a single link type piston-crank. This is because it works close to that of the connecting rod in the mechanism.
[0030]
In the single link type piston-crank mechanism, the value of the linkage ratio (the length of the connecting rod / the length of the crank arm) cannot be made smaller than 2.0 due to the problem of interference between the piston and the crankshaft. On the other hand, in the piston-crank mechanism of the present embodiment, the locus of the movement connection point B (the upper end portion of the first connection link 52) accompanying the reciprocating motion of the piston 30 is the movement connection point C (the lower end portion of the first connection link 52). The problem does not occur even if it overlaps the circumference that is the locus of). This is because there is no interference between the piston 30 and the crankshaft 40 (FIG. 1) because the second connection link 54 exists. Therefore, the value of the linkage ratio (the length of the first connecting link 52 / the length of the crank arm portion 44) can be set to 2.0 or less. However, also in this embodiment, the value of the linkage ratio cannot be made smaller than 1.0.
[0031]
Further, as described above, the value of the deflection angle φ in the present embodiment is in a smaller range than that of the single link type piston-crank mechanism, so that the side pressure acting on the piston can be kept small.
[0032]
FIG. 3 is an explanatory view showing an example of specific dimensions of the piston-crank mechanism in the embodiment. The value of the reaming ratio is 1.19, which is a value between 1.0 and 2.0.
[0033]
FIG. 4 is an explanatory diagram showing the relationship between the crank angle and the piston speed when the rotational speed of the crankshaft is 2000 revolutions per minute. FIG. 4A shows the relationship between the crank angle and the piston speed. FIG. 4B shows the relationship between the crank rotation angle from the top dead center and the piston speed. The curve represented by the solid line in FIG. 4 is the characteristic of the piston-crank mechanism of the embodiment shown in FIG. 3, and the curve represented by the broken line in FIG. It is the characteristic of the single link type piston-crank mechanism (comparative example) comprised so that it may become. From FIG. 4A, the top dead center is a point at a crank angle of about 15 degrees in the present embodiment, and a point at a crank angle of 0 degrees in the single link type piston-crank mechanism of the comparative example. Therefore, the curve represented by the solid line in FIG. 4B is equivalent to the curve represented by the solid line in FIG. 4A translated in the negative direction by about 15 degrees of the crank angle. FIG. 4B shows that the piston speed after top dead center is higher in this example than in the comparative example. For example, when the crank rotation angle from the top dead center is 10 degrees, the piston speed is 2.727 meters per second in the present embodiment, whereas in the comparative example single-link piston-crank mechanism, the piston speed is downward. It is 2.005 meters per second. Since the piston speed before the top dead center is also higher in this embodiment than in the comparative example, the piston speed change rate (that is, the slope of the curve) near the top dead center is higher in this embodiment than in the comparative example. It can also be said.
[0034]
3, the axial center line of the second connecting link 54 is parallel to the axial center line of the cylinder 20 when the crank rotation angle from the top dead center is about 10 degrees. As described above, the axial center line of the second connecting link 54 is preferably configured to be parallel to the axial center line of the cylinder 20 after the top dead center. This is because the side pressure acting on the piston is made as small as possible. That is, the combustion load acting on the piston in the expansion stroke becomes maximum after top dead center. Accordingly, when the combustion load is large, if the angle formed by the axial center line of the cylinder 20 and the axial center line of the second connecting link 54 is reduced, the side pressure acting on the piston is reduced. This is because it can be made as small as possible. “After the top dead center” means that the crank rotation angle value from the top dead center is preferably a value in the range of 0 ° to 90 °, and a value in the range of 0 ° to 20 °. Further preferred. For example, when the crank rotation angle from the top dead center is 10 degrees, in this embodiment, the value of the deflection angle φ is 0.5 degrees and the value of the side pressure is 0.4 kN, whereas the single link type of the comparative example In the piston-crank mechanism, the value of the deflection angle φ is 3.207 degrees and the value of the side pressure is 2.6 kN.
[0035]
As shown in FIG. 2, the axial center line (line ZZ) of the cylinder 20 is offset such that the distance from the fulcrum D is closer than the drive shaft 42 (fulcrum E) of the crankshaft 40. It is preferable. This is because the angle formed by the axial center line of the cylinder 20 and the axial center line of the second connecting link 54 at the time of the maximum combustion load is reduced, and the side pressure acting on the piston is reduced. Because. That is, for example, when the line ZZ moves parallel to a point passing through the fulcrum E, the moving connection point A moves in the same way, and therefore the deflection angle φ becomes large, which is not preferable. At this time, it is possible to increase the length of the support link 56 to reduce the deflection angle φ, but the internal combustion engine body becomes large, and the length of the first connection link 52 needs to be set long. It is not preferable.
[0036]
As described above, in this embodiment, the piston-crank mechanism in the internal combustion engine is configured to connect the piston and the crankshaft by the multi-link connecting rod mechanism constituted by a plurality of links, and to set the linkage ratio small. Therefore, it is possible to increase the piston speed after top dead center without excessively increasing the side pressure acting on the piston.
[0037]
B. Variation:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.
[0038]
B1. Modification 1:
The piston-crank mechanism in the internal combustion engine of the present invention can be used for any piston engine including various internal combustion engines such as gasoline engines and diesel engines, and external combustion engines such as Stirling engines. The present invention can also be realized as a vehicle or a moving body equipped with such an engine.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing the configuration of a piston-crank mechanism in an internal combustion engine as one embodiment of the present invention.
FIG. 2 is an explanatory view showing a change in shape of a piston-crank mechanism accompanying movement of a piston 30;
FIG. 3 is an explanatory diagram showing an example of specific dimensions of a piston-crank mechanism in the embodiment.
FIG. 4 is an explanatory diagram showing the relationship between the crank angle and the piston speed when the rotation speed of the crankshaft is 2000 rotations per minute.
[Explanation of symbols]
20 ... Cylinder 30 ... Piston 32 ... Piston pin 40 ... Crank shaft 42 ... Drive shaft 44 ... Crank arm 46 ... Crank pin 50 ... Multi-link connecting rod mechanism 52 ... first connection link 54 ... second connection link 56 ... support link 58 ... connection pin

Claims (4)

An internal combustion engine,
A cylinder,
A piston that reciprocates in the cylinder;
A crankshaft that rotates around a drive shaft;
A multi-link connecting rod mechanism connecting the piston and the crankshaft;
With
The multi-link connecting rod mechanism is rotatably connected to the crankshaft, is rotatably connected to the first connecting link, and is connected to the piston via a piston pin. A second connection link; and a support link rotatably connected to a connection portion between the first connection link and the second connection link and fixed to a support point of the internal combustion engine body. Prepared,
An internal combustion engine, wherein a linkage ratio value represented by a ratio between a length of the first connection link and a length of a crank arm portion of the crankshaft is set to a value of 1.0 or more and 2.0 or less. The internal combustion engine according to claim 1,
The multi-link connecting rod mechanism is an internal combustion engine configured such that an axial center line of the second connection link is parallel to an axial center line of the cylinder after the top dead center of the piston. An internal combustion engine according to claim 1 or claim 2,
An internal combustion engine in which an axial center line of the cylinder is offset such that a distance from the support point of the internal combustion engine body is closer than a drive shaft of the crankshaft. An internal combustion engine,
A cylinder,
A multi-link piston-crank mechanism;
With
The multi-link piston-crank mechanism includes a piston that reciprocates in the cylinder, a crankshaft that rotates about a drive shaft, and a multi-link connecting rod mechanism that connects the piston and the crankshaft by a plurality of links. And comprising
The multi-link piston-crank mechanism is closer to the top dead center of the piston than a single-link piston-crank mechanism configured so that the stroke of the piston has the same value as the multi-link piston-crank mechanism. An internal combustion engine configured to increase a piston speed change rate.

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